Reagent ion selector and method for soft ionization trace gas detection
Patent Information
- Application Number
- CN202611027915.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-10
- Publication Date
- 2026-10-30
AI Technical Summary
传统方案可以采用四极杆质量过滤器进行试剂离子选择，但四极杆结构、射频/直流稳定区控制、机械同轴度和真空集成会增加小型化在线设备的复杂度
[0016]本发明包括但不限于如下有益效果：（1）与传统四极杆试剂离子选择结构相比，本发明不依赖四极杆稳定区作为主要分离机理，而是利用目标试剂离子成对反向横向冲量抵消和非目标离子相位滑移偏转实现选择。该结构可作为软电离VOC检测仪的紧凑型前级离子门；（2）与单级时间偏转离子门相比，本发明可优选采用多级不同编码参数或同一物理级的多种可切换编码模式，能够降低单一周期性相位调制带来的旁瓣通带风险，提高对邻近质量离子和离子源副产物的抑制能力；（3）本发明可在H3O+、NO+、O2+等试剂离子模式之间快速切换，使同一气体样品在不同软电离反应路径下被检测，从而提高对VOC、异味气体、工业泄漏气体、呼气标志物和食品顶空挥发物的靶向识别能力。
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Figure CN123017842A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of ion optics and mass spectrometry analysis technology, specifically relating to a reagent ion selector and method for the detection of trace gases by soft ionization. Background Technology
[0002] Soft ionization trace gas detection techniques, such as selected ion flow tube mass spectrometry and proton transfer reaction mass spectrometry, often utilize predetermined reagent ions to induce ion / molecular reactions with volatile organic compounds in the sample gas. Commonly used reagent ions include protonated water ions (H₃O⁺), nitric oxide ions (NO⁺), and oxygen molecules (O₂⁺). Different reagent ions have different reaction pathways and selectivities, thus they can be used to expand the range of detectable compounds and improve the qualitative and quantitative capabilities of complex gas samples.
[0003] In such instruments, ion sources or plasma sources typically generate multiple ions and ion clusters simultaneously. To ensure controllability of the reaction path in the subsequent reaction zone, it is usually necessary to select a single reagent ion or a predetermined combination of reagent ions after the ion source, and to suppress other byproduct ions, water cluster ions, neighboring mass ions, and sidelobe crosstalk. Traditional solutions can use quadrupole mass filters for reagent ion selection, but the quadrupole structure, RF / DC stabilization control, mechanical coaxiality, and vacuum integration increase the complexity of miniaturized online equipment.
[0004] For portable or online VOC monitoring devices, there is a need for an electrically controlled, magnetic-free, and rapidly switchable reagent ion mode pre-selection module. This module does not need to perform full-spectrum mass analysis of unknowns; instead, it should stably release reagent ions at a few known target m / z values and exclude non-target ions from the calibrated target pass-through window, thereby improving the selectivity, stability, and contamination resistance of the downstream reaction zone and detector. Summary of the Invention
[0005] To address the shortcomings of existing technologies, the present invention aims to provide a reagent ion selector and method for the detection of trace gases by soft ionization.
[0006] According to one aspect of this application, a reagent ion selector for the detection of trace gases by soft ionization is disclosed, the reagent ion selector being disposed between a soft ionization ion source and a downstream reaction zone, comprising: An ion source interface is used to receive a mixed ion beam containing multiple reagent ions and byproducts generated by the soft ion source. At least one phase-slip selection stage is arranged along the ion flight direction. Each phase-slip selection stage includes two or more paired action units connected in series. Each paired action unit includes a first transverse electric field action region and a second transverse electric field action region. The first transverse electric field action region is used to apply a first time-function transverse electric field, and the second transverse electric field action region is used to apply a second time-function transverse electric field with opposite polarity to the first time-function transverse electric field and with a preset delay. The time-function transverse electric field is a transverse electric field that changes periodically with time. An inlet beam conditioning and synchronization gating unit is used to restrict the ion beam entering the phase-slip selection stage within a predetermined inlet phase window; The calibrated target is set at the outlet side of the phase-slip selection stage through a window for screening target reagent ions; A lateral collection unit is used to absorb or extract non-target reagent ions that deviate from the target and pass through the window; The downstream reaction zone interface is used to inject target reagent ions through the target through the window into the downstream reaction zone; The controller stores a set of encoded parameters corresponding to different target reagent ions. The controller controls the driving waveform of the first transverse electric field region and the second transverse electric field region according to the set of encoded parameters, so that the transverse impulse obtained by the target reagent ion in the first transverse electric field region and the second transverse electric field region is canceled and falls into the target passage window, or controls the non-target ions to generate phase slip due to the difference in mass-to-charge ratio, so that the transverse impulse cannot be canceled and deviates from the target passage window.
[0007] In some embodiments, the target reagent ion includes one or more of H3O+, NO+, and O2+.
[0008] In some embodiments, the controller stores a table of encoded parameters for multiple reagent ion modes. The controller switches between different reagent ion modes according to the sampling sequence and synchronously adjusts the triggering timing of the inlet beam conditioning and synchronization gating unit so that it maintains a predetermined synchronization relationship with the modulation phase of the selected reagent ion mode.
[0009] In some embodiments, the first and second transverse electric field regions are each formed by a pair of opposing plate electrodes, and the mixed ion beam passes through the channel between the opposing plate electrodes; the length of a single plate electrode along the ion flight direction is 3 mm to 10 mm, the axial center distance between the first and second transverse electric field regions is 5 mm to 30 mm, the distance between the two opposing inner edges of the channel is 6 mm to 16 mm, and a single phase-slip selection stage contains 2 to 20 of the paired action units.
[0010] In some embodiments, the selector includes two or more phase-slide selection stages connected in series, with different phase-slide selection stages employing different modulation frequencies, phase steps, delay coefficients, or target positions calibrated through windows.
[0011] In some embodiments, the phase-slip selection stage is located in a differential pumping region, a low-pressure ion optics region, or a pre-stage region where the mean free path is sufficient to maintain the coherence of ion time-of-flight.
[0012] In some embodiments, the downstream reaction zone interface is connected to a selected ion flow tube, a proton transfer reaction drift tube, a chemical ionization reaction chamber, an ion migration tube, a mass spectrometer, or an ion counter. The downstream reaction zone interface includes one or more of the following: a deceleration electrode, an electrostatic lens, a buffer gas thermalization zone, an ion funnel, an orifice injection structure, or a drift field matching electrode. It is used to inject selected target reagent ions with target reaction energy and beam state into the selected ion flow tube, proton transfer reaction drift tube, chemical ionization reaction chamber, ion migration tube, mass spectrometer, or ion counter connected to the downstream reaction zone interface.
[0013] In some embodiments, the phase-slip selection stage further includes a driving unit, which includes one or more of a multi-channel phase-synchronous high-voltage amplifier, a waveform generator, a delay phase-locked loop unit, an impedance matching network, and a shielded feedthrough structure; the plate electrode is provided with one or more of a guard ring electrode, a ground shield, an end compensation electrode, a finite-width compensation structure, or a calibration lookup table compensation.
[0014] In some embodiments, the lateral collection unit includes a grounded absorption plate, a negatively pressured collection electrode, or a beam-limiting slit for absorbing or exporting ion source byproducts, adjacent mass ions, or hydrated cluster ions that have not passed through the target passage window.
[0015] According to another aspect of this application, a method for detecting trace gases by soft ionization is also disclosed, the method being performed based on the reagent ion selector for detecting trace gases by soft ionization as described in any of the preceding claims, the method comprising: S1 receives a mixed ion beam containing various reagent ions and byproduct ions generated by a soft ionization ion source through an ion source interface. S2, control the inlet beam conditioning and synchronous gating unit to condition the mixed ion beam, and through synchronous gating or bundle control, make the mixed ion beam enter the phase-slip selection stage within the predetermined inlet phase window; S3, the phase-slip selection stage is controlled to load corresponding phase-slip encoding parameters according to the mass-to-charge ratio and reference kinetic energy of the target reagent ion. A first time function transverse electric field is applied to the first transverse electric field region, and a second time function transverse electric field with opposite polarity and a preset delay is applied to the second transverse electric field region. This causes the transverse impulses obtained by the target reagent ion in the first and second transverse electric field regions to be canceled, and the ion falls into the calibrated target pass window to screen out the target reagent ion. Non-target ions are caused to undergo phase slip due to the difference in mass-to-charge ratio. The transverse impulses cannot be canceled and they are transversely deflected, deviating from the target pass window and being absorbed or extracted. S4, the selected target reagent ions are injected into the downstream reaction zone.
[0016] The present invention includes, but is not limited to, the following beneficial effects: (1) Compared with the traditional quadrupole reagent ion selection structure, the present invention does not rely on the quadrupole stable region as the main separation mechanism, but uses the pairwise reverse transverse impulse cancellation of target reagent ions and the phase slip deflection of non-target ions to achieve selection. This structure can be used as a compact front-stage ion gate for soft ionization VOC detectors; (2) Compared with single-stage time deflection ion gates, the present invention can preferably use multiple levels of different coding parameters or multiple switchable coding modes of the same physical level, which can reduce the sidelobe passband risk caused by single periodic phase modulation and improve the suppression ability of adjacent mass ions and ion source byproducts; (3) The present invention can quickly switch between reagent ion modes such as H3O+, NO+, and O2+, so that the same gas sample can be detected under different soft ionization reaction paths, thereby improving the targeted recognition ability of VOCs, odor gases, industrial leaked gases, breath markers and food headspace volatiles. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.
[0018] Figure 1 This is a schematic diagram of the system connection of the present invention in a soft ionization trace gas detector; Figure 2 A schematic diagram of the plate electrode structure and main dimensions of a phase-slip pairing unit; Figure 3 A schematic diagram of the delayed drive waveforms with opposite polarities in the first and second action regions; Figure 4 This is a screenshot of SIMION in H3O+ mode according to an embodiment of this application; Figure 5 This is a screenshot of SIMION in NO+ mode according to an embodiment of this application; Figure 6 This is a screenshot of SIMION in O2+ mode according to an embodiment of this application; Figure 7 This is a slit verification diagram in the H3O+ mode of an embodiment of this application; Figure 8 This is a slit verification diagram in NO+ mode according to an embodiment of this application; Figure 9 This is a slit verification diagram under the O2+ mode of an embodiment of this application. Detailed Implementation
[0019] The terms "first," "second," "third," "fourth," etc. (if present) in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" or "having" and any variations thereof are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.
[0020] For ease of understanding, the specific process of the embodiments of the present invention is described below. Specifically, this solution discloses a reagent ion selector for the detection of trace gases by soft ionization. The reagent ion selector is disposed between the soft ionization ion source and the downstream reaction zone, and includes: An ion source interface is used to receive a mixed ion beam containing multiple reagent ions and byproducts generated by the soft ion source. At least one phase-slip selection stage is arranged along the ion flight direction. Each phase-slip selection stage includes two or more paired action units connected in series. Each paired action unit includes a first transverse electric field action region and a second transverse electric field action region. The first transverse electric field action region is used to apply a first time function transverse electric field, and the second transverse electric field action region is used to apply a second time function transverse electric field with opposite polarity to the first time function transverse electric field and with a preset delay. The time function transverse electric field is a transverse electric field that changes periodically with time, and the second time function has a delay relative to the first time function. The delay is determined based on the mass-to-charge ratio of the target reagent ion and the reference kinetic energy.
[0021] The inlet beam conditioning and synchronization gating unit is used to confine the ion beam entering the phase-slip selection stage within a predetermined inlet phase window. Specifically, when the target reagent ion passes sequentially through the first and second action regions within the predetermined inlet phase window, the lateral impulses it gains in the two regions approximately cancel each other out, causing the target reagent ion to fall into the calibrated target passage window at the selection stage exit. Non-target ions, due to their different mass-to-charge ratios, have different flight velocities, resulting in phase slip between paired action regions. Their two lateral impulses cannot cancel each other out, thus producing residual lateral deflection.
[0022] The calibrated target is set at the outlet side of the phase-slip selection stage through a window for screening target reagent ions; A lateral collection unit is used to absorb or extract non-target reagent ions that deviate from the target and pass through the window; The downstream reaction zone interface is used to inject target reagent ions through the target through the window into the downstream reaction zone; The controller stores coded parameter sets corresponding to different target reagent ions. Based on these coded parameter sets, the controller controls the driving waveforms of the first and second transverse electric field regions. This causes the transverse impulses gained by the target reagent ions in both regions to cancel each other out and fall into the target passage window. Alternatively, it controls non-target ions to experience phase shifts due to differences in mass-to-charge ratios, preventing the transverse impulses from canceling out and causing them to deviate from the target passage window. The system connection relationships in a soft ionization trace gas detector can be found in [reference needed]. Figure 1 .
[0023] Specifically, this scheme sets the control model as follows: Let the mass-to-charge ratio of the target reagent ion be... If the reference kinetic energy is U0, then the reference velocity can be expressed as: Formula 1:
[0024] Where τ0 is the nominal flight delay time of the target reagent ion between the first and second transverse electric field regions, and C is the unit conversion constant. If the axial distance between the paired transverse electric field regions is L, then the nominal delay of the target ion is: Formula 2:
[0025] The actual control delay can be written as: Formula 3:
[0026] Wherein, τ dThe delay actually applied by the controller to the driving waveform in the second transverse electric field region is represented by β, which is a compensation coefficient used to compensate for edge field, initial energy error, or mechanical error. For non-target ions, the phase slip can be expressed as: Formula 4:
[0027] Where f is the modulation frequency. The target reagent ion satisfies the transverse impulse cancellation condition, while non-target ions exhibit residual transverse deflection due to different phase slip amounts.
[0028] The lateral position of the exit of the j-th phase slip selection stage can be represented as: Formula 5:
[0029] Where y in This refers to the horizontal position of the entrance. For the entrance angle, D j F is the equivalent drift amplification factor. j The residual lateral offset generated by the j-th level encoding, code j This represents the group of coding parameters used in the j-th phase-slip selection stage, including the transverse electric field amplitude, modulation frequency, phase step, and delay coefficient. If the target calibrated in the j-th stage passes through the window center c... j Half width is a j The condition is: Formula 6:
[0030] Multi-level cascading can be represented by the following function: Formula 7:
[0031] The controller selects multiple sets of different codes to make the target reagent ions meet the target passage conditions of the passage function, and to make non-target ions deviate from the calibrated target passage window in at least one stage.
[0032] Furthermore, in some embodiments, the target reagent ion includes one or more of H3O+, NO+, and O2+.
[0033] In some embodiments, the controller stores a table of encoded parameters for multiple reagent ion modes. The controller switches between different reagent ion modes according to the sampling sequence and synchronously adjusts the triggering timing of the inlet beam conditioning and synchronization gating unit so that it maintains a predetermined synchronization relationship with the modulation phase of the selected reagent ion mode.
[0034] In some embodiments, the first and second transverse electric field regions are each formed by a pair of opposing plate-shaped electrodes, and the mixed ion beam passes through a channel between the opposing plate-shaped electrodes; adjacent pairs of first and second transverse electric field regions are spaced apart along the ion flight direction, and each receives a time-function voltage of opposite polarity. The plate-shaped electrode structure and main dimensional relationships can be found in [reference needed]. Figure 2 The waveform for the opposite polarity delay drive can be found in [reference needed]. Figure 3 The plate-shaped electrode can be disposed within a grounded shield housing. The length of a single plate-shaped electrode along the ion flight direction is 3mm to 10mm. The axial center distance between the first and second transverse electric field action regions is 5mm to 30mm. The distance between the two opposite inner edges of the channel is 6mm to 16mm. A single phase-slip selection stage contains 2 to 20 of the paired action units. The axial length of a single selection module can be 50mm to 300mm. For a positive ion beam in the 1000eV range, the amplitude of the transverse electric field between the plates can be in the range of several V / mm to hundreds of V / mm. The corresponding electrode voltage difference can be calculated based on the inner edge distance of the ion channel, and the target's position through the window can be calibrated using a downstream slit, a detection window, or an electrostatic fine-tuning electrode. The plate-shaped electrode can also be equipped with a retaining ring electrode, an end compensation electrode, a grounded shield, a finite-width compensation structure, or a calibration lookup table to compensate for edge fields and assembly errors.
[0035] In some embodiments, the selector includes two or more phase-slip selection stages connected in series. Different phase-slip selection stages employ different modulation frequencies, phase steps, delay coefficients, or target pass-through window calibration positions. When multiple selection stages are set, different selection stages can use different encoding parameters to ensure that the target reagent ion passes through the calibrated window in each stage, and the sidelobe passbands of non-target ions do not overlap in different selection stages.
[0036] In some embodiments, to avoid the loss of predictability in velocity, phase, and energy distribution due to frequent collisions within the selection stage, the phase-slip selection stage is located in a differential pumping region, a low-pressure ion optical region, or a pre-stage region with a mean free path sufficient to maintain the time-of-flight coherence of ions.
[0037] In some embodiments, the downstream reaction zone interface is connected to a selected ion flow tube, a proton transfer reaction drift tube, a chemical ionization reaction chamber, an ion migration tube, a mass spectrometer, or an ion counter. The downstream reaction zone interface includes one or more of the following: a deceleration electrode, an electrostatic lens, a buffer gas thermalization zone, an ion funnel, an orifice injection structure, or a drift field matching electrode. This interface is used to inject selected target reagent ions at target reaction energy and beam state into the selected ion flow tube, proton transfer reaction drift tube, chemical ionization reaction chamber, ion migration tube, mass spectrometer, or ion counter connected to the downstream reaction zone interface. By selecting different reagent ions, the volatile organic compounds to be measured can undergo proton transfer, charge transfer, hydrogen ion extraction, or addition reactions, thereby improving the targeted detection capability of complex gas samples.
[0038] In some embodiments, the phase-slip selection stage further includes a driving unit, which includes one or more of a multi-channel phase-synchronous high-voltage amplifier, a waveform generator, a delay phase-locked loop unit, an impedance matching network, and a shielded feedthrough structure. The controller uniformly calibrates the voltage amplitude, phase, and delay of each operating region. The plate electrode is provided with one or more of a guard ring electrode, a ground shield, an end compensation electrode, a finite-width compensation structure, or a calibration lookup table compensation.
[0039] In some embodiments, the lateral collection unit includes a grounded absorption plate, a negatively pressured collection electrode, or a beam-limiting slit for absorbing or exporting ion source byproducts, adjacent mass ions, or hydrated cluster ions that have not passed through the target passage window.
[0040] In one example, the controller stores or generates a table of encoded parameters for multiple reagent ion modes. These reagent ion modes include at least H3O+, NO+, and O2+ modes. The controller switches between different reagent ion modes according to the target detection method or sampling sequence, and maintains a predetermined relationship between the modulation phase of the synchronization gating unit and the corresponding mode, allowing the corresponding target reagent ion to enter the downstream reaction zone.
[0041] Furthermore, for ease of understanding, this solution will be described in detail with reference to the following embodiments: In one embodiment, the ion source is a microwave plasma source, and its working gas is a mixture of air and water vapor. The plasma source generates a mixed ion beam containing H3O+, NO+, O2+, and hydrated clusters. The mixed ion beam enters a multi-coded phase-slip reagent ion selector via an inlet beam conditioning unit.
[0042] The controller loads H3O+ mode parameters, causing the m / z19 ions, after synchronous gating, to fall into the calibrated target passage window in multiple selection stages, while m / z18, m / z20, and other non-target ions deviate from the target passage window in at least one stage. The selected H3O+ ions are injected into the flow tube after being coupled with downstream deceleration, heating, focusing, or buffer gas, and undergo proton transfer reactions with VOCs in the sample gas.
[0043] The controller can also load NO+ mode parameters to allow m / z30 ions to pass through a calibrated window and suppress neighboring or byproduct ions such as m / z28, m / z29, m / z31, and m / z32. The controller can also load O2+ mode parameters to allow m / z32 ions to pass through a calibrated window and suppress NO+ and neighboring mass interference.
[0044] By switching between H3O+, NO+, and O2+ modes according to the time sequence, the same instrument can obtain VOC targeted responses under different reaction pathways, improving the ability to identify isomers, background interference, and overlapping reaction pathways.
[0045] In another embodiment, the ion source primarily generates H3O+ reagent ions, but also contains H3O+(H2O)n water clusters and other water-related ions. A multi-coded phase-slip reagent ion selector is positioned in the differential vacuum region or low-pressure pre-stage ion optics region between the ion source and the drift tube to enhance the distinction between H3O+ and water clusters or byproduct ions. The selected H3O+ can be decelerated, heated, or focused before entering the drift tube, making the reagent ion composition entering the drift tube more stable.
[0046] In another embodiment, the downstream detector is not a complete mass spectrometer, but an ion counter, ion migration detector, or fixed mass window detector. This invention serves as a pre-stage reagent ion gate, injecting reagent ions into the reaction zone according to a preset pattern, and achieving targeted alarm for industrial leaked gases, malodorous gases, or breath markers through downstream signal changes.
[0047] Furthermore, to verify the manufacturable implementation, this embodiment establishes a finite-size real electrode model in SIMION, rather than directly applying an ideal virtual electric field. The simulation model uses a two-dimensional planar potential array to approximate the axial cross-section of the plate electrode, with an axial modeling length of 100 mm; the exit slit / absorption surface is located at x=95 mm, and the detection surface is located at x=97 mm. Six paired action units are arranged along the ion flight direction, each unit including upper and lower plate electrodes of the first action region and upper and lower plate electrodes of the second action region. The axial length of a single electrode is 4 mm, the axial distance between the first and second action regions is 7 mm, the inner edge spacing of the ion channel is 10 mm, the electrode thickness is 2 mm, and grounded shielding rails are provided on the upper and lower sides. This simulation geometry and Figure 2The plate electrode configuration shown is consistent; a screenshot of SIMION in the three H3O+ mode can be found here. Figure 4 See screenshots of SIMION in NO+ mode. Figure 5 See screenshots of SIMION in O2+ mode. Figure 6 The verification items for the model and bunching conditions are shown in Table 2. The Lua program applies time-varying voltages to each electrode number only through `segment.fast_adjust()`, and the electric field is obtained by solving the finite electrode plate using SIMION. The forward selection results in the simulation adopt the condition of phase locking between the inlet bunch and the driving waveform, corresponding to the operating mode of the upstream synchronous gating or bunching unit. Figure 4 The target m / z is 19, and the interference mass is 18 and 20.
[0048] The simulation used conditioning bundle conditions: inlet lateral position y = -0.005, 0, 0.005 mm, kinetic energy 999.5, 1000, 1000.5 eV, emission angle -0.05, 0, 0.05 degrees, 27 rays per mass, and the initial RF phase at the inlet was set to the phase-locked reference value. The target passage window was calibrated according to the actual assembled beamline position; when the ion reached the exit slit / absorption surface at x = 95 mm, if the lateral position after deducting the inlet beamline drift fell into the calibrated target passage window, it continued to fly to the detection surface at x = 97 mm; otherwise, it was recorded as being laterally absorbed or blocked and the trajectory was terminated. The simulation results of the local mass window for three typical reagent ions are shown in Table 1; the corresponding SIMION screenshots are shown in Table 1. Figures 4 to 6 See the slit verification diagrams respectively. Figures 7 to 9 The trajectory statistics index is shown in Table 3, the simulation coding parameters are shown in Table 4, and the mass-by-mass passage / blockage statistics of each mass ion at the exit slit are shown in Table 5. Among these, Figure 4 In the middle, the target m / z is 19, and the interference mass is 18 and 20; Figure 5 In the middle, the target m / z is 30, and the interference masses are 28, 29, 31, and 32; Figure 6 In the middle, the target m / z is 32, and the interference masses are 30, 31, 33, and 34; Figures 7 to 9 In the diagram, the red vertical line represents the x = 95 mm exit slit / absorption surface, the black dashed line represents the x = 97 mm detection surface, and the red hollow dots represent ions blocked at the slit. Figure 7 In the middle, the target m / z is 19, the interference mass is 18 and 20; the target ion passes through 27 / 27 and is detected to reach 27 / 27; the interference ion passes through 0 / 54. Figure 8 In the middle, the target m / z is 30, and the interference masses are 28, 29, 31, and 32; the target ion passes through 27 / 27 and is detected to reach 27 / 27; the interference ion passes through 0 / 108. Figure 9In the middle, the target m / z is 32, and the interference mass is 30, 31, 33, and 34; the target ion passes through 27 / 27 and is detected to reach 27 / 27; the interference ion passes through 0 / 108.
[0049] Table 1. Simulation results of real electrodes within the local mass window.
[0050] Under the same finite electrode model and phase-locked inlet conditions, further verification of typical far-end masses and hydration cluster interference was conducted, and the statistical results are shown in Table 7. In the H3O+ mode, m / z values of 18, 20, 30, 32, 37, 55, and 73 did not pass through the exit slit; in the NO+ mode, m / z values of 18, 19, 28, 29, 31, 32, 37, and 55 did not pass through the exit slit; and in the O2+ mode, m / z values of 18, 19, 30, 31, 33, 34, 37, and 55 did not pass through the exit slit. Each mass still used 27 conditioning rays.
[0051] To verify the inlet phase sensitivity, an 8-point scan of the initial radio frequency phase was performed, and the statistical results are shown in Table 6. The scan shows that if the continuous ion beam enters the selection stage with a random initial phase, the target passage and interference suppression will change significantly with the initial phase. Therefore, this embodiment and claims use the synchronous inlet gating or tufting unit as an engineering limitation to ensure that the ions entering the first action region are within a predetermined phase window; this invention does not advocate obtaining the same selection results under conditions of unsynchronized continuous ion beams.
[0052] Combining Tables 1 to 7 and Figures 4 to 6 , Figures 7 to 9 The verification results show that in soft ionization reagent ion selection applications, the phase-slip selector can establish encoding parameters for preset reagent ions, allowing the target reagent ions to pass through the calibrated target passage window and reach the downstream detection surface under phase-locked conditioning bundle conditions. Simultaneously, adjacent mass ions, water cluster mass ions, or related byproduct ions are blocked at the exit slit / absorption surface, preventing them from entering the downstream channel. These simulation results demonstrate the feasibility of the reagent ion selection front-end and are not intended to claim that this device is a full-spectrum mass spectrometer for unknown substances, nor are they intended to achieve the same results under unconditioned wide-beam, wide-dispersion, or random-phase continuous ion beam conditions. When the inlet lateral dimension, energy dispersion, or angular dispersion increases, the separation of target ions and interfering ions can be maintained by enhancing inlet beam conditioning, adjusting the amplitude of the interplate lateral electric field, adjusting the target passage window half-width, increasing the selection order, using different encoding parameters, or sacrificing flux.
[0053] Table 2 Simulation Model and Bundle Condition Verification
[0054] Table 3. Index of SIMION Images, Slit Verification Maps, and Trajectory Statistics
[0055] Table 4 Simulation coding parameters for three reagent ion modes
[0056] Table 5. Statistics on Quality Verification of Exit Slits
[0057] The supplementary verification uses the same finite electrode SIMION model. The initial phase scan is used to determine whether synchronous inlet gating is required; the typical far-end quality and hydration cluster interference verification is used to check whether the hydration cluster and far-end interference quality pass through the exit slit under phase-locked inlet conditions.
[0058] Table 6 RF Initial Phase Scan Verification Statistics
[0059] Table 7. Typical Remote Quality and Hydration Cluster Interference Verification Statistics
[0060] Phase scan results explanation: Target passage and interference suppression will change under random initial phase conditions. Therefore, this paper uses synchronous entry gating or clustering units as engineering constraints; typical far-end quality and hydration cluster interference verification only correspond to phase-locked entry conditions.
[0061] Slit verification instructions: aperture_hits.csv records the passage or blockage results of each ion at the x=95mm exit slit / absorption surface; arrivals.csv only records ions that have passed through the slit and continue to reach the x=97mm detection surface.
[0062] According to another aspect of this application, a method for detecting trace gases by soft ionization is also disclosed, the method being performed based on the reagent ion selector for detecting trace gases by soft ionization as described in any of the preceding claims, the method comprising: S1 receives a mixed ion beam containing various reagent ions and byproduct ions generated by a soft ionization ion source through an ion source interface. S2, control the inlet beam conditioning and synchronous gating unit to condition the mixed ion beam, and through synchronous gating or bundle control, make the mixed ion beam enter the phase-slip selection stage within the predetermined inlet phase window; S3, the phase-slip selection stage is controlled to load corresponding phase-slip encoding parameters according to the mass-to-charge ratio and reference kinetic energy of the target reagent ion. A first time function transverse electric field is applied to the first transverse electric field region, and a second time function transverse electric field with opposite polarity and a preset delay is applied to the second transverse electric field region. This causes the transverse impulses obtained by the target reagent ion in the first and second transverse electric field regions to be canceled, and the ion falls into the calibrated target pass window to screen out the target reagent ion. Non-target ions are caused to undergo phase slip due to the difference in mass-to-charge ratio. The transverse impulses cannot be canceled and they are transversely deflected, deviating from the target pass window and being absorbed or extracted. S4, the selected target reagent ions are injected into the downstream reaction zone.
[0063] Specifically, the H3O+, NO+, and O2+ modes are switched according to a time sequence to obtain the response of the same sample gas under different soft ionization reaction paths. The target passage window is calibrated based on the beamline position after inlet beam conditioning, allowing target reagent ions to enter the calibrated target passage window while deflecting non-target interfering ions away from it. This method is used for online VOC monitoring, industrial leak alarms, breath marker detection, food headspace volatiles detection, or semiconductor process exhaust gas monitoring.
[0064] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A reagent ion selector for the detection of trace gases by soft ionization, characterized in that, The reagent ion selector is positioned between the soft ionization ion source and the downstream reaction region, and includes: An ion source interface is used to receive a mixed ion beam containing multiple reagent ions and byproducts generated by the soft ion source. At least one phase-slip selection stage is arranged along the ion flight direction. Each phase-slip selection stage includes two or more paired action units connected in series. Each paired action unit includes a first transverse electric field action region and a second transverse electric field action region. The first transverse electric field action region is used to apply a first time-function transverse electric field, and the second transverse electric field action region is used to apply a second time-function transverse electric field with opposite polarity to the first time-function transverse electric field and with a preset delay. The time-function transverse electric field is a transverse electric field that changes periodically with time. An inlet beam conditioning and synchronization gating unit is used to restrict the ion beam entering the phase-slip selection stage within a predetermined inlet phase window; The calibrated target is set at the outlet side of the phase-slip selection stage through a window for screening target reagent ions; A lateral collection unit is used to absorb or extract non-target reagent ions that deviate from the target and pass through the window; The downstream reaction zone interface is used to inject target reagent ions through the target through the window into the downstream reaction zone; The controller stores a set of encoded parameters corresponding to different target reagent ions. The controller controls the driving waveform of the first transverse electric field region and the second transverse electric field region according to the set of encoded parameters, so that the transverse impulse obtained by the target reagent ion in the first transverse electric field region and the second transverse electric field region is canceled and falls into the target passage window, or controls the non-target ions to generate phase slip due to the difference in mass-to-charge ratio, so that the transverse impulse cannot be canceled and deviates from the target passage window.
2. The reagent ion selector for the detection of trace gases by soft ionization according to claim 1, characterized in that, The target reagent ions include one or more of H3O+, NO+, and O2+.
3. The reagent ion selector for soft ionization trace gas detection according to claim 1, characterized in that, The controller stores a table of encoded parameters for multiple reagent ion modes. The controller switches between different reagent ion modes according to the sampling sequence and synchronously adjusts the triggering timing of the inlet beam conditioning and synchronization gating unit to maintain a predetermined synchronization relationship with the modulation phase of the selected reagent ion mode.
4. The reagent ion selector for the detection of trace gases by soft ionization according to claim 1, characterized in that, The first and second transverse electric field regions are each formed by a pair of opposing plate electrodes. The mixed ion beam passes through the channel between the opposing plate electrodes. The length of a single plate electrode along the ion flight direction is 3 mm to 10 mm. The axial center distance between the first and second transverse electric field regions is 5 mm to 30 mm. The distance between the two opposing inner edges of the channel is 6 mm to 16 mm. A single phase-slip selection stage contains 2 to 20 of the paired action units.
5. The reagent ion selector for the detection of trace gases by soft ionization according to claim 1, characterized in that, The selector includes two or more phase-slide selection stages connected in series. Different phase-slide selection stages use different modulation frequencies, phase steps, delay coefficients, or target positions calibrated through windows.
6. The reagent ion selector for the detection of trace gases by soft ionization according to claim 1, characterized in that, The phase-slip selection stage is located in the differential pumping region, the low-pressure ion optics region, or the pre-stage region where the mean free path is sufficient to maintain the coherence of ion flight time.
7. The reagent ion selector for the detection of trace gases by soft ionization according to claim 1, characterized in that, The downstream reaction zone interface is connected to a selected ion flow tube, a proton transfer reaction drift tube, a chemical ionization reaction chamber, an ion migration tube, a mass spectrometer, or an ion counter. The downstream reaction zone interface includes one or more of the following: a deceleration electrode, an electrostatic lens, a buffer gas thermalization zone, an ion funnel, an orifice injection structure, or a drift field matching electrode. It is used to inject selected target reagent ions with target reaction energy and beam state into the selected ion flow tube, proton transfer reaction drift tube, chemical ionization reaction chamber, ion migration tube, mass spectrometer, or ion counter connected to the downstream reaction zone interface.
8. The reagent ion selector for the detection of trace gases by soft ionization according to claim 1, characterized in that, The phase-slip selection stage further includes a drive unit, which includes one or more of the following: a multi-channel phase-synchronous high-voltage amplifier, a waveform generator, a delay phase-locked loop unit, an impedance matching network, and a shielded feedthrough structure; the plate electrode is provided with one or more of the following: a guard ring electrode, a ground shield, an end compensation electrode, a finite-width compensation structure, or a calibration lookup table compensation.
9. The reagent ion selector for the detection of trace gases by soft ionization according to claim 1, characterized in that, The lateral collection unit includes a grounded absorption plate, a negative pressure collecting electrode or a beam-limiting slit, used to absorb or export ion source byproducts, adjacent mass ions or hydrated cluster ions that have not passed through the target passage window.
10. A method for detecting trace gases by soft ionization, characterized in that, The method is performed based on the reagent ion selector for soft ionization trace gas detection according to any one of claims 1-10, and includes: S1 receives a mixed ion beam containing various reagent ions and byproduct ions generated by a soft ionization ion source through an ion source interface. S2, control the inlet beam conditioning and synchronous gating unit to condition the mixed ion beam, and through synchronous gating or bundle control, make the mixed ion beam enter the phase-slip selection stage within the predetermined inlet phase window; S3, the phase-slip selection stage is controlled to load corresponding phase-slip encoding parameters according to the mass-to-charge ratio and reference kinetic energy of the target reagent ion. A first time function transverse electric field is applied to the first transverse electric field region, and a second time function transverse electric field with opposite polarity and a preset delay is applied to the second transverse electric field region. This causes the transverse impulses obtained by the target reagent ion in the first and second transverse electric field regions to be canceled, and the ion falls into the calibrated target pass window to screen out the target reagent ion. Non-target ions are caused to undergo phase slip due to the difference in mass-to-charge ratio. The transverse impulses cannot be canceled and they are transversely deflected, deviating from the target pass window and being absorbed or extracted. S4, the selected target reagent ions are injected into the downstream reaction zone.